The hope of overcoming a major barrier to widespread testing for one of sport's most troublesome performance-enhancing drugs, human growth hormone, has been dealt a setback with the failure of two independent research efforts to find a urine test for HGH.

Manassas-based Ceres Nanosciences and prominent anti-doping scientist Don Catlin in Los Angeles recently concluded projects that had sought an alternative to the current blood test for HGH, which has been controversial among professional sports officials and others because it is invasive, less practical than urine testing and not fully developed.

"It's going to be extremely hard to detect it in urine; I think the scientists all agree to that," said David Howman, director general of the World Anti-Doping Agency.

The results of the two projects make it clear that U.S. professional sports leagues under pressure to implement HGH testing will have to draw blood from their players -- which historically has been a non-starter for all of the U.S. sports leagues' players unions -- using a test that has had limited success, if they hope to at least deter the use of HGH in the near future.

Major League Baseball already is considering implementing blood testing for HGH at the minor league level, a move that could bring about a fresh look at the issue for MLB's players association.

Besides preferring a urine test, some sports officials have questioned the effectiveness of the current HGH blood test, which has a detection window of just 24 to 48 hours after use and has caught just one athlete in the more than six years it has been used.

Though some 1,500 HGH tests have been administered since the 2004 Athens Games, the only athlete to test positive was a British rugby player snagged by an out-of-competition test.

Howman said anti-doping officials intend to address the efficacy concerns within the year by supplementing the current HGH test with a second testing prong -- also a blood test -- that will increase the detection window to about two weeks.

"That [current] window of opportunity to detect it is quite tiny," Howman acknowledged.

But the prospects of ever finding a bullet-proof urine test for HGH look bleak; the three-year, Catlin-led project jointly funded by MLB and the National Football League demonstrated that "there's far less growth hormone in urine than we really thought," Catlin said Saturday.

The other urine-centered research project funded by the U.S. Anti-Doping Agency and led by scientists at Ceres Nanosciences ended with the prospects of developing a validated urine test at least five to 10 years away, according to USADA Chief Executive Travis Tygart.

"It's miles away from proving doping," Tygart said by phone from Lausanne, Switzerland.

Catlin contended that finding an HGH urine test remained possible but that "you have to find a new paradigm." He said the research involving nanoparticle capture technology undertaken at Ceres Nanosciences under George Mason University professors Emanuel Petricoin and Lance Liotta showed innovation and "has a lot of possibilities."

Indeed, Ceres Nanosciences Chief Executive Thomas Dunlap said his team's work had been successful in isolating HGH in urine, but remained in the initial stages.

"We're not stuck in terms of the ability to do it; we just don't have any funding for the next phase," Dunlap said.

Rob Manfred, MLB's executive vice president for labor relations and human resources, said MLB would continue to have an interest in -- and preference for -- a urine test, but in the short term the issue of whether to implement the current HGH blood test at the minor league level is "one of the active projects on my desk right now."

Professional sports leagues in the United States test their athletes for steroids and amphetamines, but none does any blood testing, so they cannot test for HGH, which a 2007 report by a commission led by former Sen. George Mitchell revealed to be a drug of choice among major league players in recent years.

Howman said WADA hoped within the next year to improve the current HGH test by combining it with an indirect test -- one that examines markers for HGH use without actually finding the HGH -- developed years ago by British scientists Peter Sonksen and Richard Holt.

The Sonksen/Holt test has a detection window of at least 10 to 14 days.

Howman said he hoped a tandem HGH test would be ready for implementation by late this year or early in 2011.

"You combine those two [tests], and we've got a very solid window of detection," Tygart said.

Manfred said MLB would consider continued funding for research into finding a urine test through the Partnership for Clean Competition, a joint anti-doping organization created by the NFL, MLB, USADA and the USOC. Dunlap said Ceres would apply for a grant; Catlin proposed a meeting to discuss the science.